Comparison of non–targ-CD39, targ-CD39, and controls in inhibiting platelet aggregation measured by light transmission aggregometry. (A) Representative aggregometry traces. ScFv-CD39 constructs were administered after preactivation of platelets with 2 µM ADP at time point 0. After 3 minutes (time point 1), scFv-CD39 constructs were added at various, activity-matched concentrations (eg, 1.33 μg/mL matches 2.66 μg/mL). Samples were challenged with 20 µM ADP at time point 2 (3 minutes after time point 1). (B) Quantitative comparison. Bar chart showing the percent light transmission after 10 minutes of incubation with scFv-CD39 constructs or the equimolar amount of the scFv control. These assays were analyzed with 1-way repeated-measures analysis of variance with the Bonferroni posttest (n = 3; **P < .01; ***P < .001).